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SubjectRe: [PATCH] fix page_alloc for larger I/O segments (improved)
On Thu, 13 Dec 2007 19:57:29 -0500
James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

>
> On Thu, 2007-12-13 at 19:46 -0500, Mark Lord wrote:
> > "Improved version", more similar to the 2.6.23 code:
> >
> > Fix page allocator to give better chance of larger contiguous segments (again).
> >
> > Signed-off-by: Mark Lord <mlord@pobox.com
> > ---
> >
> > --- old/mm/page_alloc.c 2007-12-13 19:25:15.000000000 -0500
> > +++ linux-2.6/mm/page_alloc.c 2007-12-13 19:43:07.000000000 -0500
> > @@ -760,7 +760,7 @@
> > struct page *page = __rmqueue(zone, order, migratetype);
> > if (unlikely(page == NULL))
> > break;
> > - list_add(&page->lru, list);
> > + list_add_tail(&page->lru, list);
>
> Could we put a big comment above this explaining to the would be vm
> tweakers why this has to be a list_add_tail, so we don't end up back in
> this position after another two years?
>

Already done ;)

--- a/mm/page_alloc.c~fix-page_alloc-for-larger-i-o-segments-fix
+++ a/mm/page_alloc.c
@@ -847,6 +847,10 @@ static int rmqueue_bulk(struct zone *zon
struct page *page = __rmqueue(zone, order, migratetype);
if (unlikely(page == NULL))
break;
+ /*
+ * Doing a list_add_tail() here helps us to hand out pages in
+ * ascending physical-address order.
+ */
list_add_tail(&page->lru, list);
set_page_private(page, migratetype);
}
_


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